Coincident electrofission of uranium-238 in the region of the giant resonances

Using the high duty-cycle Superconducting Electron Accelerator at Stanford, the author has measured both inclusive and coincident electrofission cross sections in uranium-238 at beam energies ranging from 45 to 165 MeV. He have determined the absolute inclusive cross sections at 47.6, 80.3, and 118.4 MeV by normalizing them to simultaneously collected elastic scattering spectra. This method agrees within errors with a direct measurement of the cross section. The data agree with the most recently published results and extend them to high energies. Although the data fall below all other published results at 80 and 118 MeV, they are consistent with virtual photon theories which take into account the finite size of the nucleus. In the more important coincidence experiment, the author has mapped out the excitation spectrum and the angular distribution in fission angle from fission threshold at 6 MeV to 25 MeV for beam energies of 80.3, 118.4, and 163.8 MeV, with scattered electrons detected at 40 degrees from the beam direction. The resulting momentum transfers (q = 0.26, 0.04, and 0.55 fm-1) correspond roughly to the first maxima of the E1, E2, and E3 form factors respectively